More Power to Atom Interferometry

Abstract

We propose and demonstrate a new scheme for atom interferometry, using light pulses inside an optical cavity as matter wave beam splitters. The cavity provides power enhancement, spatial filtering, and a precise beam geometry, enabling new techniques such as low power beam splitters (< 100 μW), large momentum transfer beam splitters with modest power, or new self-aligned interferometer geometries utilizing the transverse modes of the optical cavity. As a first demonstration, we obtain Ramsey-Raman fringes with > 75% contrast and measure the acceleration due to gravity, g, to 60 μg= ffiffiffiffiffiffi Hz p resolution in a Mach-Zehnder geometry. We use > 10 7 cesium atoms in the compact mode volume (600 μm 1=e 2 waist) of the cavity and show trapping of atoms in higher transverse modes. This work paves the way toward compact, high sensitivity, multiaxis interferometry. DOI: 10.1103/PhysRevLett.114.100405 PACS numbers: 03.75.Dg, 06.30.Gv, 37.25.+k, 37.30.+i In a light-pulse atom interferometer, recoils from photonatom interactions are used to split and interfere matter waves (see Fig. 1). These interferometers have been used to measure the gravitational accelerationg [1], rotationΩ [2], gravity gradients [3], the fine structure constant [4], Newton's gravitational constant [5,6], and absolute masses in a proposed revision of the SI [7,8], to test Einstein's equivalence principle [9][10][11][12], and have been proposed to measure the free fall of antimatter [13] and to detect gravitational waves [14][15][16]. The sensitivity of a conventional Mach-Zehnder interferometer increases with the measured phase difference(whereṽ 0 is the initial velocity of the atom), which scales with the pulse separation time T and the recoil momentum p ¼ ℏk eff , wherek eff is the effective wave number of the photons. State of the art atom interferometers are limited by several engineering boundaries. T is limited by the free-fall time in atomic fountains, which are now as high as 10 m [17,18]. Multiphoton interactions can increase the recoil momentum to a multiple nℏk of the single photon recoil [19][20][21][22][23] but are limited by the available laser power (e.g., 6 W in [24], 43 W in [25]). Finally, wave front distortions spread the local wave vector around its mean, lowering interference contrast and reducing both sensitivity and accuracy. An optical cavity can solve these problems by providing spatial filtering to clean the wave fronts and enhancing laser intensity. However, running an atom interferometer inside an optical cavity presents challenges in keeping the atoms in the relatively small cavity mode volume and having multiple laser frequencies (needed due to recoil frequency shifts, Doppler shifts, and atomic structure) simultaneously resonant with the cavity. Here, we present a cesium atom interferometer inside an in-vacuum optical cavity and demonstrate gravity measurements using less than 100 μW of laser power incident on the cavity.The use of an optical cavity has many advantages. First, laser power limits interferom...

Fast Control of Atom-Light Interaction in a Narrow Linewidth Cavity

“…This method opens perspectives to push the use of atomic cavities in long baseline atom interferometers, such as proposed for GW detection, and to exploit high-finesse cavities to improve the spatial filtering of the coherent manipulation beams [11]. This can be used for shorter pulses, large-momentum-transfer atom optics, and may even lead to universal AI [42]. High-finesse cavities can also be used for quantum enhanced measurements [32,35,[43][44][45][46], and could open new avenues for the creation of macroscopic quantum states in optomechanics, by providing a fast and deterministic way to control the transparency of a BEC [47].…”

Fast control of atom-light interaction in a narrow linewidth cavity

“…This method opens perspectives to push the use atomic cavities in long baseline atom interferometers, such as proposed for GW detection, and to exploit high finesse (narrow linewidth) cavities to improve the spatial filtering of the coherent manipulation beams [11]. This can be used for shorter pulses, large momentum transfer atom optics, and may even lead to universal AI [42]. High finesse cavities can also be used for quantum enhanced measurements [31,34,[43][44][45], and could open new avenues for the creation of macroscopic quantum states in optomechanics, by providing a fast and deterministic way to control the transparency of a BEC [46].…”